Filter agitating means and method



" Feb. 2,. 1943.

c. E. PALMER FILTER AGITATING MEANS AND METHOD F iipd Odt. 9,,[1939 a hosts-Sheet IN VEN TOR.

FIG I CHARLES EDWARD PALMER XZZMM' 4 Hi5 ATTORNEY.

Feb. 2,1943.

0. EfPALMER 2,309,917

FILTER AGITA'IING MEANS AND METHOD F iled Oct. 9, 1939' 5 "Sheets-Sheet 2 FIG 6- IN VEN TOR.

CHARFES EDWARD PALMER H15 A TTORNEX Feb. 2, 1943. 41E. PALMER 2,309,917

FILTER AGITAIING MEANS- AND METHOD 2 Fil ed Oct. 9, 1939. s Sheets-Sheet s.

' INVENTOR. CHARLES EDWARD PALMER m5- ATTORNEY Patented Feb. 2 1943 UNITED STATES PATENT OFFICE FILTER. AGITATI'NG MEANS A METHOD I Charles Edward Palmer, Erie, Pa. Application October 9, 1939, Serial No. 298,611

3 Claims.

This invention relates to agitating means employed when back-washing a filter bed, and more particularly to an improved rotating and construction and increased agitating eifect with rotary agitating means.

In a co-pending application Serial Number 229,431 filed September 12, 1938, entitled Agitating means and methods for filter beds, I described a method and means for increasing the agitation of filter material during a back-washing operation wherein a rotating a'rm operating with the filter material in aflooded state projects jets of water into the filter material. This permits a relatively low velocity of back-wash water to be used which together with the increased agitation caused by the rotating jets efiects a considerably greater scrubbing action of the filter material with a relatively large reduction in th amount of back-wash water required.

In the aforementioned construction the jets were provided by forcing water through perforated plugs disposed in convention-a1 T cou- 'plings joining a plurality of short lengths of pipe extending laterally from a supporting bearing. The perforations were equally spaced along the arm on each side of the axis of rotation of the arm. In the aforementioned construction I did not provide a jet at the axis of rotation of the arm.

In the present construction the nozzles on each side of the arm axis are staggered or placed at unequal distances from the axis of rotation of the arm whereby one jet does not track anthe agitating effect in a manner to be hereinafter described I havefurther found that the aforementioned staggering of the nozzles and the improved nozzle construction together with the provision of a nozzle at the arm axis provides increased circulation and agitation in a vertical zone concurj rently with and supplementing the circulation and agitation in a horizontal zone. I have found that due to the improved construction above described that individual filter particles are caused to travel a tortuous path of considerable distance in a given period thereby eflectively scrubbing the particles.

It is a primary object of my invention to provide improved rotary type agitating means for a filter bed.

Another object of my invention is to provide, an improved method of agitating a filter bed during a back-wash operation.

Another object of my invention is to provide an improved construction for a rotating arm type agitating means for filter beds.

Another object ofmy invention is to provide an improved rotary type agitating means for filter beds wherein a given area is more effectively treated with a given number of nozzles.

Another object of my invention isto provide an improved nozzle construction for a rotating arm used in filter bed agitation and method of securing the nozzle to the arm.

Another object of my invention is to provide a method of agitating a filter bed during a backwash operation whereby individual filter particles are required to travel a considerable distance in a given period and in a manner to encounter other particles.

Other objects of my invention and the invention itself will become increasingly apparent from a consideration of the following description and drawings wherein Fig. 1 is a plan view of a filter bed embodying my invention with supporting pipesomitted for clearness of illustration;

Fig. 2 is a section taken along line 2-2 of Fig. 1;

Fig. 3 is a section along line 3-3 of Fig. 1;

Fig. 4 is a section along line 4-4 of Fig. 1;

Fig. 5 is a diagrammatic plan view of a filter bed showing the movement of filter material;

Fig. 6 is a section along line 66 of Fig. 1 showing the manner in which agitation is effected, V

Fig. 7 is a fragmentary elevational view showing a modified position of the agitating means;

Fig. 8 is a longitudinal sectional view of a pressure filter embodying my invention and Fig. 9 is a section along line 99 of Fig. 8.

Referring now to the drawings and particularly Figs. 1, 5 and 6, I have indicated generally at H! a filter unit which may comprise one of a plurality of units. The filter bed may be of any well known construction and constitutes no essential part of my invention. For illustration I have shown the bed as comprising a base li, a perforated false bottom I2, a rear wall IS, a front wall l4, and side walls l5 and it. The unit in its lower portion is provided with gravel or the like I I of successively smaller size proceeding upwardly which supports a layer of filtering material such as sand, coal particles or the. like.

' The usual flume is indicated at l3 and troughs at IS. A conduit connects with flume I8 and a conduit 2| opens into the space between base II and false bottom l2. Valves 22 control flow through conduit 20 and valves 23 through con- Preferably supported by rear wall l3 and flume wall Ha is a pipe 25 having a bearing 23 adjacent its lower extremity and supporting a laterally extending arm 21. Bearing 26 threadedly or otherwise sealingly engages a T member 28, member 23 having pipe portions 23 and 30 seallngly secured laterally thereto. Reducing nipples 3| secure pipe portions .32 and 33 to pipe portions 23 and 30 respectively.

Although I preferably reduce the cross sectional area of the arm at the outer portions to compensate for pressure loss it is understood that this is not essential and the arm may be of uniform internal diameter throughout its length.

T member 28 as best illustrated in Figs. 2 and 3, is bored preferably at any angle substantially 15 degrees downwardly from a horizontal plane and a nozzle 34 is threaded or otherwise sealingly secured therein. Although I preferably disposethe nozzles downwardly at substantially-15 degrees since a downwardly directed jet increases the effective depth of the scrubbing action I contemplate that any desired arrangement of the nozzles may be used. However, when relying on the unbalanced hydraulic force of the Jets for rotating the arm, the rotating effect is diminished asthe angle of inclination is increased and I have found an angle of substantially 15 degrees to give the most efllcient results as to both agitation and rotation.

In Fig. 4 I have shown a preferred method of securing nozzles indicated at 35 t0 the pipe portlons 23, 30, 32 and 33 wherein the pipe wall is not normally of sufiicient thickness to effect a secure threaded joint. The pipe wall is drilled and a bushing 36 has a reduced portion 31 in serted therein, the enlarged flange portion of the bushing abutting the pipe outer surface at diametrically opposite portions. The bushing is then fixed to the pipe preferably by welding as indicated at 38, the weld extending around the flange periphery and along the flange walls as indicated to present a streamlined surface when rotating. Bushing 36 is internally threaded to receive the threaded stem of nozzle 35. It will be noted that nozzles 34 and 35 have tapering outer surfaces and also a relatively small tapered bore. I have found that by providing a nozzle construction of this type that the frictional resistance to arm movement is not only considerably decreased but that the jets issuing from the nozzles extend outwardly a substantial distance from, the arm before spreading.

Additionally, the vertical component of the jets issuing from nozzles 34 and 35 diminishes the load on the bearing due to the agitating arm parts when the agitating arm is in operation.

Referring to Fig, 1, it will be noted that the nozzles 35 associated with the left hand portion of the arm are spaced at difierent distances from the arm axis than the nozzles 35 associated with the right hand portion of the arm. Thus, the

path of a left disposed nozzle will be intermediate adjacent paths of right disposed nozzles resulting in a more effective agitation and scrubbing of the filter particles for an arm of a given length and .with a given number of nozzles than when the nozzles are equally spaced relative to the arm axis. It will also be noted that the nozzles are disposed relatively closer together as the outer ends of the arm are approached to compensate for the increased bed area covered by the outer portions of the arm. At the arm outer ends I preferably provide nozzles 33 having a flange portion welded or otherwise suitably secured to the arm and adapted to direct jets substantially axially outwardly of the arm.

The nozzle adjacent the-arm axis of rotation will revolve in a path indicated at 43 and will tend to cause the filter particles to move outwardly' along a tangent indicated at ll and whereby these particles will' be moved into the path of the next adjacent nozzle relative to the arm axis and the process will be repeated with particle movement being accelerated as the particles move outwardly due to the increased rotational speed of the jets. Thus, the particles in a zone adjacent the arm axis will tend to move towards the walls of the bed and the paths of particles moving outwardly will cross as indicated at 42 resulting in a scrubbing inter-action between particles. v

The movement of filter particles is further 11- lustrated in Figs. 5 and 6. In Fig. 5 paths of filter particles are shown in plan view wherein a particle initiating its movement at the central portion of the bed will move outwardly along a path indicated at 43 and upon encountering the unit wall it will tend to move along the wall with the circulating water as indicated at 43a and at the same time will tend to drop by'gravity until forced, inwardly along a path 43b with water moving to replace water displaced by centrifugal action from the central portion of the bed. A similar path of a, more outwardly disposed par-' ticle is indicated at 44, a and b and these paths will cross as indicated at a: which. is a desired result for scrubbing actio After the arm passes a given portion of the bed, the effective force of the jets in this portion of the bed will be temporarily removed and this causes the filter medium particles to tend to drop despite the upward force of the low velocity backwash water. In Fig. 6 I have shown a vertical view of paths 4:, 43a, 43b, 44; (Maud ub wherein it will be noted that the particles tend to drop to a point below the eflective penetration of the downwardly directed jets when returning to the central portion ofthe bed. The manner in which the particles travel can be illustrated by allowing the agitator to rotate as the backwash water flow is stopped and I have found that upon then stopping the agitator thatthesand or other filter medium does not level off but that the filter medium will be low at the center and heaped against the outer walls of the filter. This clearly indicates that the filter medium particles are caused to move outwardly from the center portion of the filter towards the filter walls and during operation of both the agitator and the back wash these particles will be returned to replace other particles in the center portion of the bed generally in the manner indicated. This same result occurs when the agitator is operated without the use of backwash water.

In certain localities at certain periods of the year algae is encountered which tends to form a mat on the top surface of the filter and prevent filtering. It has some times been attempted to relieve this condition by bumping the -filter or suddenly applying, relatively high velocity backwash but this frequently causes a volcanic action with resultant cracks in the filter matetively used during normal filtering operations to increase filtering efficiency when it is not desired to cease filtering and resort to backwash in conjunction with the agitator to clean the bed.

Referring to Fig. 6 it will be noted that the agitator arm 21 is disposed beneath thenormal level of filter medium during the filtering proc ess indicated at 48 and during the backwash op-- eration the filter medium particles will be expanded to a height such as indicated at 49 and I the jets will be operating at some distance below the level 48. In Fig. 7 I have shown the a itator arm 21 as disposed above the normal leve 45 of the filter medium and during a backwash operation the jets will be operating in'the zone between the level 48 and the expanded level 49. The arm 21 may be disposed at any desired relative height but the construction illustrated in Fig. 6-permits of a more effective penetration of the jets. i-

I appreciate that the paths of individual particles as illustrated in Figs. 1, and 6 will be influenced by encountering other particles but in general the particles will tend to move along the paths indicated. It will be observed that the particles are caused to travel a considerable distance in a short period and in a manner to encounter numerous other particles which insures 'a highly eflicient agitation and scrubbing action as contrasted with the conventional backwash method wherein the particles tend to be carried directly upwardly by the backwash water and drop by gravity or remain suspended, the particles traversing limited generally parallel paths. In employing a hydraulically driven arm, as shown, the rotation of the arm is influenced by the reactive force of the jets so that the rotational effect is adjusted to varying densities of suspended filter particles in water.

I have found that unusual occurrences in the process of operating the agitator may impose undue and unexpected strains upon the agitator arms, such as water hammer caused by air leaks in the system. Also, the tendency of the filter medium particles to pile up at the filter walls places considerable strain on the outer ends of the arms and to care for such strains, I have provided a T coupling 28 of the form shown in Fig. 2 wherein the coupling arm portions 45 are extended beyond the threaded portion to give added support to pipes 29 and 30 as indicated at 41. Also, I preferably provide an abutting fiat shoulder 48 in coupling 28 to engage the inner ends of pipes 29 and 30.

Referring to Fig. 3 I have shown in dotted lines a nozzle 34a which I may optionally secure to T coupling 28 and disposed to direct a jet of water beneath the coupling whereby any tendency to create a dead zone as 'to agitation beneath the coupling is eliminated. Normally, the provision of a nozzle 34a is not required since water.

the ackwash stream breaks unsuch a zone but when treating certain types of liquid such a con struction may be desired. I

Referring to Figs. 8 and 9 I have shownthe rotary agitating means applied to a pressure type filter generally indicated at 50. The filter it is of well known construction and comprises closed cylindrical tank 5i having the lower por tion filled with a concrete or the like base 522 which supports the filter medium such as gravel 53 and sand 54. Also, supported on base 52 is preferably oval form conduit 55 having laterally extending perforated arms 58 adapted to receive filtered, water during the filtering operation and elect backwash water during the backwash operation. Water to be filtered is supplied under pressure to tank Blunder control of a valve 51 and the effluent water is controlled by a valve 58. Valves 51 and 58 willbe operated in reverse order during the backwash operation so that valve 58 controls the infiuent backwash As best illustrated in Fig. 8 a plate 59 and concrete provides a forward compartment 80 whereby water flowing into compartment 8i will be caused to enter a trough 82 and overflow onto the filter bed. The construction so far described is conventional asto pressure type filters and constitutes no essential part of my invention. The adaptation of my improved rotary agitating means to this type filter will now be described.

A supply conduit 55 supported by the ends of tank 5i and preferably centrally above trough 62 supports a pair of spaced rotary arms 21 constructed as previously described and of a length to revolve in tank 5i with proper clearance. Due to the decreased length of arms 21 the reduced pipe portions 32 and 33 may be omitted if desired. The flow of water through pipe 55 will be controlled by suitable valve means (not shown) and arms 2'! will be caused to revolve as previously described by the reactive force of the jets to increase the agitation when backwashing the filter. Although I have shown two arms 21 in this modification it is understood that any suitable number may be used and also that the agitating means may be applied in a similar manner to a vertically disposed pressure filter rather than a horizontally disposed filter as shown.

Although the agitating means described is adaptable to sand or a filter medium of lighter specific gravity than sand I have found that it is of particular value when using a relatively rough filter such as coal particles ahead of a fine filter such as sand. It is well known that an ideal filter would be a composite of a rough filter medium superposed on a fine filter of greater specific gravity insofar as filtering results ,are concerned since the tendency to clog the filter would be relatively diminished resulting in longer operating periods before cleaning the filter. After a sand filter or the like hasbeen washed it will be found that the filter medium will be graded from a coarse size at the bottom to a fine size at the top. It is well known that under these conditions practically all of the filtering or removal of turbid matter takes place at the top surface of the filtering medilim. When this top surface becomes clogged (with turbid matter A the loss of head requires washing of the filter.

It is apparent that longer runs could be obtained if the hydraulic grading which takes place as a result of the backwash 'could be reversed and the coarser filtering medium disposedat the filtering process.

It has been found that this desired filter condition can be obtained by employing two filtering mediums oi diilerent specific gravities such as a top zone of coal particles and a lower zone of sand. However, under these conditions it is found that a large part of the turbid matter accumulates on top of the finer filter media (sand) or at the inter-face oi the two filter mediums and that when a sufiicient rate or rise of backwash is used to remove this accumulation, the media 01' lower specific gravity is washed out of the filter.

I have found that by employing the rotary arm and agitation means hereinbefore described that the rate of rise of backwash can be reduced sufficiently to allow the lower specific gravity media to remain in the filter and at the same time to remove all turbid matter from the filter.

I have also found that the agitating means should be directed to react at the interface zone of the filter.

Although I have shown and described preferred forms of my invention I contemplate that numerous and extensive departures may be made therefrom without departing from the spirit of my invention and the scope of the appended claims.

What I claim is:

1. Rotary agitating means for a filter bed comprising a fixed'liquid supply conduit, a conduit arm rotatably suspended from and solely supported by said supply conduit, a plurality oi nozzles spaced along the arm, the nozzles on one side or the arm axis being adapted to direct liquid jets in a given direction and those on the other side of the arm axis being adapted to direct jets in the opposite direction, the nozzles on one side of the arm axis being spaced at different distances from said axis than the nozzles.

at the other side of the arm axis, and means for supplying liquid under pressure to the arm. 2.- The combination with a closed pressure filter including a trough disposed above the nor-- mal level of filter media in the filter oi' agitating means comprising a liquid supply conduit projected into said filter above the trough, a vertical conduit communicating with the supply conduit and projected through the trough, a horizontal arm rotatably supported by the vertical conduit, and a plurality of nozzles spaced along said arm and adapted to direct jets of water in opposite directions at each side of the arm axis and having a composite reactive force adapted to drive said arm solely by the reactive force when the nozzles are supplied with liquid under pressure in excess of normal back-wash liquid pressure.

3. The combination as described in .claim 2 and wherein a plurality of vertical conduits are supported by the supply conduit and projected through the trough, and each of said vertical conduits rotatably supports an arm.

CHARLES EDWARD PALMER. 

